Czech scientists monitoring a green frog population in the Odra River Basin for twenty years have yet to find a female of the species. Known in Czech as the Skokan zelený (which translates as “Green Jumper”), the species are found in wetlands throughout Europe, and also known as the Common Water Frog, Green Frog – or Edible Frog. While they are on the menu in France, in the Czech Republic they are protected by law as a highly endangered species. Only in the Poodří wetlands is there a purely male population. How can this be? The Institute of Animal Physiology and Genetics at the Czech...